R - ordered factor over multiple columns

Question

I'm pretty brand new to R, so please excuse any R grammer errors here...

I have a 19 question likert survey saved in a data frame (19 columns). The responses are numeric and converted to characters.

I would like to change the Likert scores to factor and specify levels. I can do this with each column individually, but wondering how to use a loop to apply this to all columns without having to repeat this line of code 19 times for all columns

My current code

lik_tab$lik_01 <- factor(lik_tab$lik_01,
                          levels = c("1", "2", "3", "4", "5"),
                            ordered = TRUE)

I know I can repeat that for the next columns "lik_02", lik_03"... and so on, but how do I write this more succinctly?

I tried lapply with the following error:

lik_tab <- lapply(lik_tab,factor(levels = c("1", "2", "3", "4", "5"),
+                                      ordered = TRUE))
Error in match.fun(FUN) : 
  'factor(levels = c("1", "2", "3", "4", "5"), ordered = TRUE)' is not a function, character or symbol

Thanks!

Answer 1

If we wrap with the function call, use anonymous function, also while assigning to the full dataset, use [] to keep the structure of the dataset, otherwise, it would be a list output from the lapply

lik_tab[] <- lapply(lik_tab, function(x) factor(x, 
                   levels = c("1", "2", "3", "4", "5"),
                                  ordered = TRUE))

Otherwise, we can just specify the parameters

lik_tab[] <- lapply(lik_tab, factor, levels = c("1", "2", "3", "4", "5"),
                                   ordered = TRUE)